EP-A-432 101 describes a circuit arrangement for supplying power to a plurality of angular-displacement sensors and for switching the values measured by the latter to a display which includes as an essential component an analog multiplexer which, if addressed in a suitable manner, transfers, on the one hand, a sinusoidal or pulse-shaped alternating voltage to the angular-displacement sensor to be selected and, on the other hand, the output signal from this sensor to an electronic evaluating unit.
Due to the specific kind of these sensors, the circuit arrangement described requires two supply lines and four measurement-signal lines per sensor, so that the analog multiplexer has one sixfold through-switching path per sensor.
Magnetic flow sensors, however, are only comparable to the prior art angular-displacement sensors inasmuch as they also have at least six leads, two of which are DC supply leads, while only two are measured-value leads, and two serve to transfer the coil current. Thus, the prior art circuit arrangement is not usable with magnetic flow sensors.
It is, therefore, an object of the invention to provide a circuit arrangement for operating a plurality of magnetic flow sensors with a single electronic evaluating unit.